Monitoring Wells
The Navy's groundwater monitoring wells provide regular data on the aquifer and possible contaminants in the groundwater around the Red Hill facility. The Navy is currently working to install 22 new monitoring wells throughout the Moanalua and Halawa Valleys to expand our understanding of the aquifer.

What is a Monitoring Well?
Groundwater monitoring wells are used as an access point to the groundwater for the purpose of sampling the quality of the water in the aquifer. They range from two to four inches in diameter and reach depths down to the water table.

Monitoring wells are installed using a drill rig to breakthrough various geological layers to reach the groundwater’s surface. Drilling of these wells takes approximately 6 to 12 weeks.

Once a monitoring well is complete, it is sealed with a cap to protect the water below. Samplers are able to draw from the well using a slow flow pump to collect samples each week.


Recently completed groundwater monitoring well near Red Hill.

Types of Monitoring Wells
The Navy is installing two types of groundwater monitoring wells as part of our Red Hill environmental efforts. These wells are meant to provide information on the water quality in the aquifer.

P-Wells
Plume delineation monitoring wells or P-Wells are wells installed in the area immediately surrounding the Red Hill Shaft. The purpose of these wells is to monitor the contamination plume from the November 20, 2021 fuel release and identify concentration levels of contamination. P-Wells are two inches in diameter and reach depths below the surface of the groundwater.

S-Wells
Sentinel monitoring wells or S-Wells will be installed further out in the Moanalua and Halawa Valleys in areas between Red Hill and both the Navy and Board of Water Supply’s drinking water wells. The purpose of these wells is to provide early warning of any contamination that may spread into these areas and to ensure our drinking water sources remain safe. S-Wells are four inches in diameter and reach depths below the surface of the groundwater.